Arterial spin-labeled perfusion combined with segmentation techniques to evaluate cerebral blood flow in white and gray matter of children with sickle cell anemia.
BACKGROUND
Changes in cerebral perfusion are an important feature of the pathophysiology of sickle cell anemia (SCA); cerebrovascular ischemia occurs frequently and leads to neurocognitive deficits, silent infarcts, and overt stroke. Non-invasive MRI methods to measure cerebral blood flow (CBF) by arterial spin labeling (ASL) afford new opportunities to characterize disease- and therapy-induced changes in cerebral hemodynamics in patients with SCA. Recent studies have documented elevated gray matter (GM) CBF in untreated children with SCA, but no measurements of white matter (WM) CBF have been reported.


METHODS
Pulsed ASL with automated brain image segmentation-classification techniques were used to determine the CBF in GM, WM, and abnormal white matter (ABWM) of 21 children with SCA, 18 of whom were receiving hydroxyurea therapy.


RESULTS
GM and WM CBF were highly associated (R(2) = 0.76, P < 0.0001) and the GM to WM CBF ratio was 1.6 (95% confidence interval: 1.43-1.83). Global GM CBF in our treated cohort was 87 +/- 24 mL/min/100 g, a value lower than previously reported in untreated patients with SCA. CBF was elevated in normal appearing WM (43 +/- 14 mL/min/100 g) but decreased in ABWM (6 +/- 12 mL/min/100 g), compared to published normal pediatric controls. Hemispheric asymmetry in CBF was noted in most patients.


CONCLUSIONS
These perfusion measurements suggest that hydroxyurea may normalize GM CBF in children with SCA, but altered perfusion in WM may persist. This novel combined approach for CBF quantification will facilitate prospective studies of cerebral vasculopathy in SCA, particularly regarding the effects of treatments such as hydroxyurea.
Helton
Kathleen J
KJ
Department of Radiological Sciences, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA. kathleen.helton@stjude.org
Paydar
Amir
A
Glass
John
J
Weirich
Eric M
EM
Hankins
Jane
J
Li
Chin-Shang
CS
Smeltzer
Matthew P
MP
Wang
Winfred C
WC
Ware
Russell E
RE
Ogg
Robert J
RJ
D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000188:drug therapy / Q000503:physiopathology*; D001783:Blood Flow Velocity; D002490:Central Nervous System / Q000473:pathology* / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D002648:Child; D002675:Child, Preschool; D003952:Diagnostic Imaging; D006801:Humans; D006918:Hydroxyurea / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D009413:Nerve Fibers, Myelinated; D036421:Nerve Fibers, Unmyelinated; D011446:Prospective Studies
D006918:Hydroxyurea